fix(core): auto flush logs on synchronous internal errors

[micalevisk]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: closes #13400

What is the new behavior?

For the following code

import { NestFactory } from '@nestjs/core'
import { AppModule } from './app.module' // no-op module

async function bootstrap() {
  const app = await NestFactory.create(AppModule, {
    bufferLogs: true,
    autoFlushLogs: true,
  });
  app.get('foo')
  await app.listen(3000);
}

bootstrap();

we'll see the following error:

Do note that if autoFlushLogs is false, no logs will be shown for the above code.

Does this PR introduce a breaking change?

• Yes
• No

[coveralls]

Pull Request Test Coverage Report for Build 7aab33f9-738b-4c84-a4cb-bbe8a92bad8a

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.123%

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Totals
Change from base Build eacd3e56-4bed-4f5e-9bab-412a10335aab:	0.0%
Covered Lines:	6736
Relevant Lines:	7312

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💛 - Coveralls